Method of lubricating an internal combustion engine

ABSTRACT

The invention provides a method of lubricating a compression-ignition internal combustion engine with a maximum laden mass over 2,700 kg comprising supplying to the engine a lubricating composition comprising: an oil of lubricating viscosity, 1.5 wt % to 10 wt % of an ashless dispersant, a 300 TBN or higher alkaline earth metal sulphonate detergent having a metal ratio of 10 to 40, and a 80 TBN or lower alkaline earth metal sulphonate detergent having a metal ratio of 1 to 5, wherein the lubricating composition comprises 0 wt % to 0.2 wt % of a phenolic based detergent, the ratio of higher alkaline earth metal sulphonate detergent to lower alkaline earth metal sulphonate detergent is 80:20 to 20:80, the total amount of soap delivered by the calcium sulphonate detergents is 0.4 wt % to 1.5 wt % of the lubricating composition, and the lubricating composition has a sulphated ash content of not more than 1.5 wt %.

FIELD OF INVENTION

The invention provides a method of lubricating a compression-ignitioninternal combustion engine with a maximum laden mass over 2,700 kgcomprising supplying to the engine a lubricating composition comprising:an oil of lubricating viscosity, 1.5 wt % to 10 wt % of an ashlessdispersant, a 300 TBN or higher alkaline earth metal sulphonatedetergent having a metal ratio of 10 to 40, and a 80 TBN or loweralkaline earth metal sulphonate detergent having a metal ratio of 1 to5, wherein the lubricating composition comprises 0 wt % to 0.2 wt % of aphenolic based detergent, the ratio of higher alkaline earth metalsulphonate detergent to lower alkaline earth metal sulphonate detergentis 80:20 to 20:80, the total amount of soap delivered by the calciumsulphonate detergents is 0.4 wt % to 1.5 wt % of the lubricatingcomposition, and the lubricating composition has a sulphated ash contentof not more than 1.5 wt %.

BACKGROUND OF THE INVENTION

Phenol-based detergents are known. Among these are phenates based onphenolic monomers, linked with sulfur bridges or alkylene bridges suchas methylene linkages derived from formaldehyde. The phenolic monomersthemselves are typically substituted with an aliphatic hydrocarbyl groupto provide a measure of oil solubility. The hydrocarbyl groups may bealkyl groups, and, historically, dodecylphenol (or propylenetetramer-substituted phenol) has been widely used. An early reference tobasic sulfurized polyvalent metal phenates is U.S. Pat. No. 2,680,96,Walker et al., Jun. 1, 1954; see also U.S. Pat. No. 3,372,116,Meinhardt, Mar. 6, 1968.

Alkylphenol based detergents are known for efficacy to provide depositcontrol, antioxidancy, and assisting in reducing wear. However, certainalkylphenols and products prepared from them have come under increasedscrutiny due to their association as potential endocrine disruptivematerials. In particular, alkylphenol detergents which are based onoligomers of C 12 alkyl phenols may contain residual monomeric C12 alkylphenol species.

U.S. Pat. No. 7,943,796 (Campbell et al, 4 Feb. 2010) discloses anoverbased salt of an oligomerized alkylhydroxyaromatic compound, whereinthe alkyl group of the alkylhydroxyaromatic compound is derived from anolefin mixture comprising propylene oligomers having an initial boilingpoint of at least about 195° C. and a final boiling point of no morethan about 325° C. as measured by ASTM D86. Also disclosed is alubricating oil composition containing at least (a) a major amount of anoil of lubricating viscosity and (b) the overbased salt of theoligomerized alkylhydroxyaromatic compound.

U.S. Pat. No. 7,435,709 (Stonebaker et al, 1 Mar. 2007) discloses alubricating oil composition displaying reduced endocrine disruptionresponse, comprising a major amount of an oil of lubricating viscosity;and a detergent comprising an unsulfurized alkali or alkaline earthmetal salt of a reaction product of (1) an olefin having at least 10carbon atoms, wherein greater than 80 mole % of the olefin is a linearC20-C30 n-alpha olefin, wherein less than 10 mole % of the olefin is alinear olefin of less than 20 carbon atoms, and wherein less than 5 mole% of the olefin is branched chain olefin of 18 carbons or less, and (2)a hydroxyaromatic compound.

U.S. Pat. No. 8,183,192 (Sinquinn et al, 4 Aug. 2011) discloses anoverbased salt of an oligomerized alkylhydroxyaromatic compound for usein a lubricating oil composition, wherein the alkyl group of thealkylhydroxyaromatic compound is derived from an olefin mixturecomprising propylene oligomers having an initial boiling point of atleast about 195° C. and a final boiling point of greater than 325° C.and up to about 400° C. as measured by ASTM D86. Also disclosed is apropylene oligomer having an initial boiling point of at least about195° C. and a final boiling point of greater than 325° C. and up toabout 400° C. as measured by ASTM D86, wherein the propylene oligomercontains a distribution of carbon atoms that comprise at least about 50weight percent of C14 to C20 carbon atoms

U.S. Pat. No. 8,207,380 (Campbell et al., 30 Oct. 2008) discloses analkylated hydroxyaromatic compound prepared by reacting at least onehydroxyaromatic compound with a branched olefinic oligomer having fromabout 20 to about 80 carbon atoms in the presence of a acid catalyst.The alkylated hydroxyaromatic compound has been determined to besubstantially free of endocrine disruptive chemicals when the effectswere quantified on pubertal development and thyroid function in theintact juvenile female rat.

U.S. Pat. No. 8,198,225 (Harrison et al., 4 Jun. 2009) discloses ansulfurized metal alkyl phenate compositions having a low alkyl phenolcontent. The sulfurized metal alkyl phenate compositions can be preparedby reacting a phenol compound of Formula (I) disclosed therein with analdehyde to form a phenolic resin of Formula (II) disclosed therein andthen by reacting the phenolic resin simultaneously with a metal base anda first sulfurizing agent. The sulfurized metal alkyl phenatecompositions and the overbased sulfurized metal alkyl phenatecompositions disclosed therein may be used as detergents for formulatinglubricating oil compositions. The lubricating oil compositions disclosedtherein have a reduced amount of the free phenol compound and a saltthereof

US Patent application 2011/0124539 (Sinquinn et al., 26 May 2011)discloses an overbased, sulfurized salt of at least one alkylatedhydroxyaromatic compound, wherein the alkyl substituent of thehydroxyaromatic compound is a residue of at least one isomerized olefinhaving from about 15 to about 99 wt. % branching is disclosed. Theoverbased, sulfurized salt of at least one alkylated hydroxyaromaticcompound is produced by the process comprising: (a) alkylating at leastone hydroxyaromatic compound with at least one isomerized olefin havingfrom about 15 to about 99 wt. % branching obtained by isomerizing atleast one normal alpha olefin having from about 10 to about 40 carbonatoms, to provide at least one alkylated hydroxyaromatic compound; (b)neutralizing and sulfurizing the alkylated hydroxyaromatic compound inany order to provide at least one neutralized, sulfurized alkylatedhydroxyaromatic compound; and (c) overbasing the at least oneneutralized, sulfurized alkylated hydroxyaromatic compound

International publication WO 2013/059173A1 (Cook et al, 25 Apr. 2013)discloses a bridged dimeric or oligomeric phenolic compound comprising:at least one monomer unit (a) of phenol or an alkyl-substituted phenolwherein the alkyl group contains 1 to 8 carbon atoms, or mixturesthereof; at least one monomer unit (b) of an aliphatichydrocarbyl-substituted phenol wherein the aliphatic hydrocarbyl groupcontains at least about 25 carbon atoms, or mixtures thereof; and atleast one sulfur-containing or carbon-containing bridging group; or asalt of said oligomeric material; wherein the average number of carbonatoms in said alkyl groups and said aliphatic hydrocarbyl groups is 10to 100.

There is interest, therefore, in developing a lubricating compositionthat may be used in diesel engines that operate under severe conditionsand loads while reducing the impact of soot and soot-related wear aswell as cleanliness and deposits.

SUMMARY OF THE INVENTION

The present invention allows for an internal combustion engine(typically a compression ignited engine) to have at least one of reducedsoot, reduced deposit formation, reduced wear and improved cleanliness.

As used herein reference to the amounts of additives present in thelubricating composition disclosed herein are quoted on an oil freebasis, i.e., amount of actives, unless otherwise indicated.

As used herein, the transitional term “comprising,” which is synonymouswith “including,” “containing,” or “characterized by,” is inclusive oropen-ended and does not exclude additional, un-recited elements ormethod steps. However, in each recitation of “comprising” herein, it isintended that the term also encompass, as alternative embodiments, thephrases “consisting essentially of” and “consisting of,” where“consisting of” excludes any element or step not specified and“consisting essentially of” permits the inclusion of additionalun-recited elements or steps that do not materially affect the basic,essential and novel characteristics of the composition or method underconsideration.

As used herein the expression “compression ignited internal combustionengine” is intended to encompass internal combustion engines that has atleast in part compression ignition. As a result the invention isintended to encompass a method of lubricating a compression ignitedinternal combustion engine, as well as spark assisted compressionignited internal combustion engines.

As used herein the term “soap” means the surfactant portion of adetergent and does not include a metal base, such as calcium carbonate.The soap term may also be referred to as a detergent substrate. Forexample, the sulphonate detergents described herein, the soap orsubstrate is a neutral salt of an alkylbenzenesulphonic acid.

As used herein all total base number values cited are determined by ASTMMethod D2896-11.

The invention relates to a method of lubricating a compression-ignitioninternal combustion engine with a maximum laden mass over 2,700 kgcomprising supplying to the engine a lubricating composition comprising:

an oil of lubricating viscosity,

1.5 wt % to 10 wt % of an ashless dispersant,

a 300 TBN or higher alkaline earth metal sulphonate detergent having ametal ratio of 10 to 40,

a 80 TBN or lower alkaline earth metal sulphonate detergent having ametal ratio of 1 to 5,

wherein the lubricating composition comprises 0 wt % to 0.2 wt % of aphenolic based detergent,

the ratio of higher alkaline earth metal sulphonate detergent to loweralkaline earth metal sulphonate detergent is 80:20 to 20:80,

the total amount of soap delivered by the calcium sulphonate detergentsis 0.4 wt % to 1.5 wt % (or 0.4 to 1 wt %, or 0.5 to 1 wt %) of thelubricating composition, and

the lubricating composition has a sulphated ash content of not more than1.5 wt %.

In another embodiment the ratio of higher alkaline earth metalsulphonate detergent to lower alkaline earth metal sulphonate detergentis 70:30 to 30:70, or 65:35 to 35:65.

In one embodiment the total amount of soap delivered by the sulphonatedetergent is 0.4 wt % to 1 wt %, or 0.5 to 0.8 wt % of the lubricatingcomposition.

In one embodiment the lubricating composition comprises 0 wt % to 0.1 wt% of a phenolic based detergent.

In a further embodiment the lubricating composition comprises 0 wt % ofa phenolic based detergent.

In one embodiment the phenolic based detergent may be a phenate.

The phenolic based detergent may be selected from of a phenate, and asalycilate.

The phenolic based detergent may be selected from of a phenate, asalycilate, and a salixarate.

The phenate may be a non-sulphur containing phenate, sulphur containingphenate, or a “hybrid” detergents formed with mixed surfactant system,wherein the hybrid is a mixed phenate-salicylate, a sulphonate-phenate,or a sulphonate-phenate-salicylate.

In one embodiment the lubricating composition comprises 0 wt % of thephenolic based detergent. In this embodiment the lubricating compositioncomprises only sulphonate detergents.

In a different embodiment the lubricating composition comprises 0.01 wt% to 0.2 wt %, or 0.05 wt % to 0.1 wt % of the phenolic based detergent.

The laden mass (sometimes referred to as gross vehicle weight rating(GVWR)) may be over 2,700 kg (or 6,000 USA pounds) 2,900 kg, or over3.00 kg, or over 3,300 kg, or over 3,500 kg, or over 3,700 kg, or over3,900 kg (or 8,500 USA pounds). Typically the upper limit on the ladenmass or GVWR is set by national government and may be 10,000 kg, or9,000 kg, or 8,000 kg, or 7,500 kg.

Heavy duty diesel engines are noted to be limited to all motor vehicleswith a “technically permissible maximum laden mass” over 3,500 kg,equipped with compression ignition engines or positive ignition naturalgas (NG) or LPG engines. In contrast, the European Union indicates thatfor new light duty vehicles (passenger cars and light commercialvehicles) included within the scope of ACEA testing section “C” have a“technically permissible maximum laden mass” not exceeding 2610 kg.

There is a distinct difference between passenger car, and heavy dutydiesel engines. The difference in size from over 3,500 kg to not morethan 2610 kg means that engines of both types will experiencesignificantly different operating conditions such as load, oiltemperatures, duty cycle and engine speeds. Heavy duty diesel enginesare designed to maximize torque for hauling payloads at maximum fueleconomy while passenger car diesels are designed for commuting peopleand acceleration at maximum fuel economy. The designed purpose of theengine hauling versus communing results in different hardware designsand resulting stresses imparted to lubricant designed to protect andlubricate the engine. Another distinct design difference is theoperating revolution per minute (RPM) that each engine operates at tohaul versus commute. A heavy duty diesel engine such as a typical 12-13litre truck engine would typically not exceed 2200 rpm while a passengercar engine can go up to 4500 rpm.

In one embodiment the internal combustion engine is a heavy duty dieselcompression ignited (or spark assisted compression ignited) internalcombustion engine.

In another embodiment the invention provides for the use of alubricating composition disclosed herein to provide at least one ofreduced soot, reduced deposit formation, reduced wear and improvedcleanliness in a compression ignited internal combustion engine(typically a diesel internal combustion engine).

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method for lubricating an internalcombustion engine and a use as disclosed above.

Oils of Lubricating Viscosity

The lubricating composition comprises an oil of lubricating viscosity.Such oils include natural and synthetic oils, oil derived fromhydrocracking, hydrogenation, and hydrofinishing, unrefined, refined,re-refined oils or mixtures thereof. A more detailed description ofunrefined, refined and re-refined oils is provided in InternationalPublication WO2008/147704, paragraphs [0054] to [0056] (a similardisclosure is provided in US Patent Application 2010/197536, see [0072]to [0073]). A more detailed description of natural and syntheticlubricating oils is described in paragraphs [0058] to [0059]respectively of WO2008/147704 (a similar disclosure is provided in USPatent Application 2010/197536, see [0075] to [0076]). Synthetic oilsmay also be produced by Fischer-Tropsch reactions and typically may behydroisomerised Fischer-Tropsch hydrocarbons or waxes. In one embodimentoils may be prepared by a Fischer-Tropsch gas-to-liquid syntheticprocedure as well as other gas-to-liquid oils.

Oils of lubricating viscosity may also be defined as specified in April2008 version of “Appendix E—API Base Oil Interchangeability Guidelinesfor Passenger Car Motor Oils and Diesel Engine Oils”, section 1.3Sub-heading 1.3. “Base Stock Categories”. The API Guidelines are alsosummarised in U.S. Pat. No. 7,285,516 (see column 11, line 64 to column12, line 10).

In one embodiment the oil of lubricating viscosity may be an API Group Ito IV mineral oil, an ester or a synthetic oil, or mixtures thereof. Inone embodiment the oil of lubricating viscosity may be an API Group II,Group III, Group IV mineral oil, an ester or a synthetic oil, ormixtures thereof.

The amount of the oil of lubricating viscosity present is typically thebalance remaining after subtracting from 100 wt % the sum of the amountof the additives of the invention and the other performance additives.

The lubricating composition may be in the form of a concentrate and/or afully formulated lubricant. If the lubricating composition of theinvention (comprising the additives disclosed herein) is in the form ofa concentrate which may be combined with additional oil to form, inwhole or in part, a finished lubricant), the ratio of the of theseadditives to the oil of lubricating viscosity and/or to diluent oilinclude the ranges of 1:99 to 99:1 by weight, or 80:20 to 10:90 byweight. Typically the lubricating composition of the invention comprisesat least 50 wt %, or at least 60 wt %, or at least 70 wt %, or at least80 wt % of an oil of lubricating viscosity.

Sulphonate Detergent

Overbased materials, otherwise referred to as overbased or superbasedsalts, are generally single phase, homogeneous Newtonian systemscharacterized by a metal content in of that which would be present forneutralization according to the stoichiometry of the metal and theparticular acidic organic compound reacted with the metal. The overbasedmaterials are prepared by reacting an acidic material (typically aninorganic acid or lower carboxylic acid, preferably carbon dioxide) witha mixture comprising an acidic organic compound, a reaction mediumcomprising at least one inert, organic solvent (mineral oil, naphtha,toluene, xylene, etc.) for said acidic organic material, astoichiometric excess of a metal base, and a promoter such as a calciumchloride, acetic acid, phenol or alcohol. The acidic organic materialwill normally have a sufficient number of carbon atoms to provide adegree of solubility in oil. The amount of “excess” metal(stoichiometrically) is commonly expressed in terms of metal ratio. Theterm “metal ratio” is the ratio of the total equivalents of the metal tothe equivalents of the acidic organic compound. A neutral metal salt hasa metal ratio of one. A salt having 3.5 times as much metal as presentin a normal salt will have metal excess of 3.5 equivalents, or a ratioof 4.5.

The “soap content”, metal ratio and TBN are known to a person skilled inthe art and explained in standard textbook entitled “Chemistry andTechnology of Lubricants”, Third Edition, Edited by R. M. Mortier and S.T. Orszulik, Copyright 2010, pages 219 to 220 under the sub-heading7.2.5. Detergent Classification.

The lubricating composition disclosed herein comprises at least twosulphonate detergents. The sulphonate detergents of the invention areknown to a person skilled in the art.

Both the lower and higher TBN sulphonate detergent defined by thepresent invention are alkaline earth metal sulphonate detergents.Typically the alkaline earth metal is chosen from calcium, magnesium, orbarium. Typically calcium, or magnesium.

The 300 TBN or higher calcium sulphonate detergent and the 80 TBN orlower calcium sulphonate detergent may be prepared from the same ordifferent hydrocarbyl-substituted sulphonic acids. Typically thehydrocarbyl-substituted sulphonic acids are alkyl-substituted sulphonicacids.

The sulphonate may be prepared from a mono- ordi-hydrocarbyl-substituted benzene (or naphthalene, indenyl, indanyl, orbicyclopentadienyl) sulphonic acid, wherein the hydrocarbyl group maycontain 6 to 40, or 8 to 35 or 9 to 30 carbon atoms.

The hydrocarbyl group may be derived from polypropylene or a linear orbranched alkyl group containing at least 10 carbon atoms. Examples of asuitable alkyl group include branched and/or linear decyl, undecyl,dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl,octadecyl, octadecenyl, nonodecyl, eicosyl, un-eicosyl, do-eicosyl,tri-eicosyl, tetra-eicosyl, penta-eicosyl, hexa-eicosyl or mixturesthereof.

In one embodiment the hydrocarbyl-substituted sulphonic acid may includepolypropene benzenesulphonic acid and C₁₆-C₂₄ alkyl benzenesulphonicacid, or mixtures thereof.

In one embodiment the 300 TBN sulphonate detergent may be apredominantly linear alkylbenzene sulphonate detergent having a metalratio of having a metal ratio of 10 to 40 as is described in paragraphs[0026] to [0037] of US Patent Application 2005065045 (and granted asU.S. Pat. No. 7,407,919). The predominantly linear alkylbenzenesulphonate detergent may be particularly useful for assisting inimproving fuel economy.

Typically the 300 TBN or higher calcium sulphonate detergent has a metalratio of 12 to 30, or 12 to 22, or 16 to 20, or 10 to 20, or 20 to 30,or 22 to 25 mg KOH/g. In one embodiment the 300 TBN metal ratio may be16 to 20, and in another embodiment 22 to 25.

The calcium sulphonate detergent having a metal ratio of 10 to 40 mayhave a TBN of 350 to 500, or 375 to 425 mg KOH/g.

For example the calcium sulphonate may have a TBN ranging from 350 to500 and a metal ratio of 20 to 30, or may have a TBN of 375 to 425 mgKOH/g; and a metal ratio of 22 to 25.

When neutral or slightly basic, a calcium sulphonate detergent may haveTBN of 1 to 80, or 1 to 75, typically 2 to 50 mg KOH/g, or 5 to 35 mgKOH/g.

The calcium sulphonate detergent having a metal ratio of 1 to 5 may havea TBN of 1 to 80, or 2 to 40, or 5 to 35 mg KOH/g. Typically the calciumsulphonate detergent having a metal ratio of 1 to 5 has a TBN of 5 to 35mg KOH/g.

In another embodiment the lubricating composition further comprisesanother sulphonate detergent, typically a magnesium, sodium or zincoverbased sulphonate. Typically any additional sulphonate detergent maybe a magnesium or sodium sulphonate detergent, with magnesium sulphonatethe more typical.

In one embodiment the lubricating composition comprises a calciumsulphonate detergent having a metal ratio of 10 to 40, and a calciumsulphonate detergent having a metal ratio of 1 to 5.

In one embodiment the lubricating composition comprises a calciumsulphonate detergent having a metal ratio of 10 to 40, a calciumsulphonate detergent having a metal ratio of 1 to 5, and a magnesiumsulphonate detergent having a metal ratio of 12 to 40.

The magnesium sulphonate detergent may have a TBN of 300 to 500, or 350to 425 mg KOH/g; and a metal ratio of 12 to 40, or 14 to 25. Themagnesium sulphonate may have the same or differenthydrocarbyl-substituted sulphonic acids, and are defined the same asdescribed above for calcium sulphonate detergents.

If present the other sulphonate (typically magnesium sulphonate)detergent may be present in an amount such as 0.01 wt % to 0.5 wt %, or0.2 wt % to 0.3 wt %. Typically the lubricating composition consists ofonly two detergents i.e., the two calcium sulphonate detergents, andoptionally a magnesium sulphonate detergent which is present or absentin different embodiment.

In one embodiment at least two of the sulphonate detergents are calciumsulphonate detergents. For example, the 80 TBN or lower alkaline earthmetal sulphonate detergent may be a calcium sulphonate, or the 300 TBNor higher alkaline earth metal sulphonate detergent may be a calcium ormagnesium sulphonate.

In one embodiment the 300 TBN or higher alkaline earth metal sulphonatedetergent comprises a calcium sulphonate detergent having a metal ratioof 10 to 40, and the 80 TBN or lower alkaline earth metal sulphonatedetergent comprises a calcium sulphonate detergent having a metal ratioof 1 to 5.

In one embodiment the 300 TBN or higher alkaline earth metal sulphonatedetergent comprises a magnesium sulphonate detergent having a metalratio of 10 to 40, and the 80 TBN or lower alkaline earth metalsulphonate detergent comprises a calcium sulphonate detergent having ametal ratio of 1 to 5.

In one embodiment the 300 TBN or higher alkaline earth metal sulphonatedetergent comprises a mixture of a calcium sulphonate detergent having ametal ratio of 10 to 40, and a magnesium sulphonate detergent having ametal ratio of 10 to 40, and the 80 TBN or lower alkaline earth metalsulphonate detergent comprises a calcium sulphonate detergent having ametal ratio of 1 to 5.

The 300 TBN or higher alkaline earth metal sulphonate detergent mixturecomprise calcium sulphonate detergent having a metal ratio of 16 to 20,and the magnesium sulphonate detergent having a metal ratio of 12 to 40.

The 300 TBN or higher alkaline earth metal sulphonate detergent mixturecomprise calcium sulphonate detergent having a metal ratio of 22 to 25,and the magnesium sulphonate detergent having a metal ratio of 14 to 25.

Ashless Dispersant

The lubricating composition contains an ashless dispersant. Typicallythe ashless dispersant comprises a Mannich dispersant, a succinamidedispersant, a polyolefin succinic acid ester, amide, or ester-amide, ormixtures thereof. In one embodiment the dispersant may be present as asingle dispersant. In one embodiment the dispersant may be present as amixture of two or three different dispersants, wherein at least one maybe a succinimide dispersant. Typically the ashless dispersant comprisesa succinimide dispersant.

The succinimide dispersant may be derived from an aliphatic polyamine,or mixtures thereof. The aliphatic polyamine may be aliphatic polyaminesuch as an ethylenepolyamine, a propylenepolyamine, a butylenepolyamine,or mixtures thereof. In one embodiment the aliphatic polyamine may beethylenepolyamine. In one embodiment the aliphatic polyamine may beselected from of ethylenediamine, diethylenetriamine,triethylenetetramine, tetraethylene-pentamine, pentaethylenehexamine,polyamine still bottoms, and mixtures thereof.

In one embodiment the ashless dispersant may be a polyolefin succinicacid ester, amide, or ester-amide. For instance, a polyolefin succinicacid ester may be a polyisobutylene succinic acid ester ofpentaerythritol, or mixtures thereof. A polyolefin succinic acidester-amide may be a polyisobutylene succinic acid reacted with analcohol (such as pentaerythritol) and a polyamine as described above.

The ashless dispersant may be an N-substituted long chain alkenylsuccinimide. An example of an N-substituted long chain alkenylsuccinimide is polyisobutylene succinimide. Typically thepolyisobutylene from which polyisobutylene succinic anhydride is derivedhas a number average molecular weight of 350 to 5000, or 550 to 3000 or750 to 2500. Succinimide dispersants and their preparation aredisclosed, for instance in U.S. Pat. Nos. 3,172,892, 3,219,666,3,316,177, 3,340,281, 3,351,552, 3,381,022, 3,433,744, 3,444,170,3,467,668, 3,501,405, 3,542,680, 3,576,743, 3,632,511, 4,234,435, Re26,433, and U.S. Pat. Nos. 6,165,235, 7,238,650 and EP PatentApplication 0 355 895 A.

The dispersants may also be post-treated by conventional methods by areaction with any of a variety of agents. Among these are boroncompounds (such as boric acid), urea, thiourea, dimercaptothiadiazoles,carbon disulphide, aldehydes, ketones, carboxylic acids such asterephthalic acid, hydrocarbon-substituted succinic anhydrides, maleicanhydride, nitriles, epoxides, and phosphorus compounds. In oneembodiment the post-treated dispersant is borated. In one embodiment thepost-treated dispersant is reacted with dimercaptothiadiazoles. In oneembodiment the post-treated dispersant is reacted with phosphoric orphosphorous acid. In one embodiment the post-treated dispersant isreacted with terephthalic acid and boric acid (as described in US PatentApplication US2009/0054278.

The ashless dispersant may have a TBN on an oil free basis of 20 ormore, 40 or more, 70 or more, or 85 or more, such as 50 to 130, or 80 to120, or 90 to 115.

The ashless dispersant may be present at 2.5 wt % to 6 wt %, or 3 wt %to 5 wt %. Typically the ahsless dispersant may comprise a succinimidedispersant, wherein the succinimide dispersant is present at. 2.5 wt %to 6 wt %, or 3 wt % to 5 wt %.

The succinimide dispersant may comprise a polyisobutylene succinimide,wherein the polyisobutylene from which polyisobutylene succinimide isderived has a number average molecular weight of 350 to 5000, or 750 to3000 or 1550 to 2500.

The polyisobutylene succinimide may have a carbonyl to nitrogen ratio of1:1 to 1:5, or 1:1 to 1:4, or 1:1.3 to 3: or 1:1.5 to 1:2.

The ashless dispersant may typically comprise a dispersant package oftwo or more dispersants. The dispersant package may comprise:

0.1 wt % to 4 wt % of a borated polyisobutylene succinimide dispersant,wherein the polyisobutylene from which the borated polyisobutylenesuccinimide is derived has a number average molecular weight of 550 to1150, and

0.1 wt % to 6 wt % of a polyisobutylene succinimide, wherein thepolyisobutylene from which polyisobutylene succinimide is derived has anumber average molecular weight of 350 to 5000, or 750 to 3000 or 1550to 2500.

The polyisobutylene succinimide derived from a polyisobutylene having anumber average molecular weight of 1550 to 2500 may be present at 0.1 to2 wt %, or 0.2 wt % to 1 wt %. In one embodiment the ashless dispersantfurther comprises a polyisobutylene succinimide derived from apolyisobutylene having a number average molecular weight of 1550 to 2500and may be present at 0.1 to 2 wt %, or 0.2 wt % to 1 wt %.

Dispersant Viscosity Modifier

The lubricating composition of the invention in one embodiment furthercontains a dispersant viscosity modifier. When present the dispersantviscosity modifier may be present at 0.05 wt % to 1.5 wt %, or 0.1 wt %to 1 wt %, or 0.1 to 0.5 wt %.

The dispersant viscosity modifier may include functionalisedpolyolefins, for example, ethylene-propylene copolymers that have beenfunctionalised with an acylating agent such as maleic anhydride and anamine; polymethacrylates functionalised with an amine, or styrene-maleicanhydride copolymers reacted with an amine. More detailed description ofdispersant viscosity modifiers are disclosed in InternationalPublication WO2006/015130 or U.S. Pat. Nos. 4,863,623; 6,107,257;6,107,258; 6,117,825; and U.S. Pat. No. 7,790,661. In one embodiment thedispersant viscosity modifier may include those described in U.S. Pat.No. 4,863,623 (see column 2, line 15 to column 3, line 52) or inInternational Publication WO2006/015130 (see page 2, paragraph [0008]and preparative examples are described paragraphs [0065] to [0073]).

In one particular embodiment the dispersant viscosity modifier comprisesan olefin copolymer further functionalised with a dispersant aminegroup. Typically, the olefin copolymer is an ethylene-propylenecopolymer.

The olefin copolymer has a number average molecular weight of 5000 to100,000, or 7500 to 60,000, or 8000 to 45,000.

The dispersant amine group may be prepared/derived from reacting theolefin copolymer (typically, an ethylene-propylene copolymer) with anacylating agent (typically maleic anhydride) and an aromatic aminehaving a primary or secondary amino group. Typically, the dispersantviscosity modifier may be an ethylene-propylene copolymer acylated withmaleic anhydride and reacted with an aromatic amine.

The formation of a dispersant viscosity modifier is well known in theart. The dispersant viscosity modifier may include for instance thosedescribed in U.S. Pat. No. 7,790,661 column 2, line 48 to column 10,line 38.

In one embodiment the dispersant viscosity modifier may be prepared bygrafting of an olefinic carboxylic acid acylating agent onto a polymerof 15 to 80 mole percent of ethylene, from 20 to 85 mole percent ofC₃₋₁₀ α-monoolefin, and from 0 to 15 mole percent of non-conjugateddiene or triene, said polymer having an average molecular weight rangingfrom 5000 to 500,000, and further reacting said grafted polymer with anamine (typically an aromatic amine).

In another embodiment the dispersant viscosity modifier may be areaction product of: (a) a polymer comprising carboxylic acidfunctionality or a reactive equivalent thereof, said polymer having anumber average molecular weight of greater than 5,000; and (b) an aminecomponent comprising at least one aromatic amine containing at least oneamino group capable of condensing with said carboxylic acidfunctionality to provide a pendant group and at least one additionalgroup comprising at least one nitrogen, oxygen, or sulfur atom, whereinsaid aromatic amine is selected from of (i) a nitro-substituted aniline,(ii) an amine comprising two aromatic moieties linked by a —C(O)NR—group, a —C(O)O— group, an —O— group, an —N═N— group, or an —SO₂— groupwhere R is hydrogen or hydrocarbyl, one of said aromatic moietiesbearing said condensable amino group, (iii) an aminoquinoline, (iv) anaminobenzimidazole, (v) an N,N-dialkylphenylenediamine, (vi), anaminodiphenylamine (also N,N-phenyldiamine), and (vii) aring-substituted benzylamine.

The aromatic amine of the dispersant viscosity modifier may also includethose which can be represented by the general structure NH₂—Ar orT-NH—Ar, where T may be alkyl or aromatic, Ar is an aromatic group,including nitrogen-containing or amino-substituted aromatic groups andAr groups including any of the following structures:

as well as multiple non-condensed or linked aromatic rings. In these andrelated structures, R^(v), R^(vi), and R^(vii) can be independently,among other groups disclosed herein, —H, —C₁₋₁₈ alkyl groups, nitrogroups, —NH—Ar, —N═N—Ar, —NH—CO—Ar, —OOC—Ar, —OOC—C₁₋₁₈ alkyl,—COO—C₁₋₁₈ alkyl, —OH, —O—(CH₂CH₂—O)_(n)C₁₋₁₈ alkyl groups, and—O—(CH₂CH₂O)_(n)Ar (where n is 0 to 10).

Aromatic amines include those amines wherein a carbon atom of thearomatic ring structure is attached directly to the amino nitrogen. Theamines may be monoamines or polyamines. The aromatic ring will typicallybe a mononuclear aromatic ring (i.e., one derived from benzene) but caninclude fused aromatic rings, especially those derived from naphthalene.Examples of aromatic amines include aniline, N-alkylanilines such asN-methylaniline and N-butylaniline, di-(para-methylphenyl)amine,4-aminodiphenylamine, N,N-dimethylphenylenediamine, naphthylamine,4-(4-nitrophenylazo)aniline (disperse orange 3), sulphamethazine,4-phenoxyaniline, 3-nitroaniline, 4-aminoacetanilide(N-(4-aminophenyl)acetamide)), 4-amino-2-hydroxy-benzoic acid phenylester (phenyl amino salicylate), N-(4-amino-phenyl)-benzamide, variousbenzylamines such as 2,5-dimethoxybenzylamine, 4-phenylazoaniline, andsubstituted versions of these. Other examples includepara-ethoxyaniline, para-dodecylaniline, cyclohexyl-substitutednaphthylamine, and thienyl-substituted aniline. Examples of othersuitable aromatic amines include amino-substituted aromatic compoundsand amines in which the amine nitrogen is a part of an aromatic ring,such as 3-aminoquinoline, 5-aminoquinoline, and 8-aminoquinoline. Alsoincluded are aromatic amines such as 2-aminobenzimidazole, whichcontains one secondary amino group attached directly to the aromaticring and a primary amino group attached to the imidazole ring. Otheramines include N-(4-anilinophenyl)-3-aminobutanamide or 3-amino propylimidazole. Yet other amines include 2,5-dimethoxybenzylamine.

Additional aromatic amines and related compounds are disclosed in U.S.Pat. Nos. 6,107,257 and 6,107,258; some of these includeaminocarbazoles, benzoimidazoles, aminoindoles, aminopyrroles,amino-indazolinones, amino-perimidines, mercaptotriazoles,aminophenothiazines, aminopyridines, amino-pyrazines, aminopyrimidines,pyridines, pyrazines, pyrimidines, amino-thiadiazoles,aminothiothiadiazoles, and aminobenzotriaozles. Other suitable aminesinclude 3-amino-N-(4-anilinophenyl)-N-isopropyl butanamide, andN-(4-anilinophenyl)-3-{(3-aminopropyl)-(cocoalkyl)amino} butanamide.Other aromatic amines which can be used include various aromatic aminedye intermediates containing multiple aromatic rings linked by, forexample, amide structures. Examples include materials of the generalstructure:

and isomeric variations thereof, where R^(viii) and R^(ix) areindependently alkyl or alkoxy groups such as methyl, methoxy, or ethoxy.In one instance, R_(viii) and R^(ix) are both —OCH₃ and the material isknown as Fast Blue RR [CAS#6268-05-9].

In another instance, R^(ix) is —OCH₃ and R^(viii) is —CH₃, and thematerial is known as Fast Violet B [99-21-8]. When both R^(viii) andR^(ix) are ethoxy, the material is Fast Blue BB [120-00-3]. U.S. Pat.No. 5,744,429 discloses other aromatic amine compounds, particularlyaminoalkylphenothiazines. N-aromatic substituted acid amide compounds,such as those disclosed in U.S. Patent Application 2003/0030033 A1, mayalso be used for the purposes of this invention. Suitable aromaticamines include those in which the amine nitrogen is a substituent on anaromatic carboxyclic compound, that is, the nitrogen is not sp²hybridized within an aromatic ring.

The aromatic amine may also comprise an amine formed by reacting analdehyde with 4-aminodiphenylamine. The resultant amine may be describedas an alkylene coupled amine having at least 4 aromatic groups, at leastone —NH₂ functional group, and at least 2 secondary or tertiary aminogroups. The aldehyde may be aliphatic, alicyclic or aromatic. Thealiphatic aldehyde may be linear or branched. Examples of a suitablearomatic aldehyde include benzaldehyde or o-vanillin. Examples of analiphatic aldehyde include formaldehyde (or a reactive equivalentthereof such as formalin or paraformaldehyde), ethanal or propanal.Typically the aldehyde may be formaldehyde or benzaldehyde.Alternatively, this aromatic amine may also be prepared by themethodology described in Berichte der Deutschen Chemischen Gesellschaft(1910), 43, 728-39.

The aromatic amine formed by coupling an aldehyde and4-aminodiphenylamine is described European Patent application EP 2 401348 A in and may also be represented by the formula:

wherein each variableR¹ may be hydrogen or a C₁₋₅ alkyl group (typically hydrogen);R² may be hydrogen or a C₁₋₅ alkyl group (typically hydrogen);U may be an aliphatic, alicyclic or aromatic group, with the provisothat when U is aliphatic, the aliphatic group may be linear or branchedalkylene group containing 1 to 5, or 1 to 2 carbon atoms; and w may be 0to 9 or 0 to 3 or 0 to 1 (typically 0).

In one embodiment the aromatic amine includes 4-aminodiphenylamine,aldehyde (typically formaldehyde) coupled 4-aminodiphenylamine,nitro-aniline (3-nitro-aniline), disperse orange-3 (D03), or mixturesthereof.

Other Performance Additives

A lubricating composition may be prepared by adding the product of theprocess described herein to an oil of lubricating viscosity, optionallyin the presence of other performance additives (as described hereinbelow).

The lubricating composition of the invention optionally comprises otherperformance additives. The other performance additives include at leastone of metal deactivators, viscosity modifiers, friction modifiers,antiwear agents, corrosion inhibitors, extreme pressure agents,antioxidants, foam inhibitors, demulsifiers, pour point depressants,seal swelling agents and mixtures thereof. Typically, fully-formulatedlubricating oil will contain one or more of these performance additives.

The lubricating composition in a further embodiment comprises anantioxidant, wherein the antioxidant comprises a phenolic or an aminicantioxidant or mixtures thereof. The antioxidants include diarylamines,alkylated diarylamines, hindered phenols, or mixtures thereof. Whenpresent the antioxidant is present at 0.1 wt % to 3 wt %, or 0.5 wt % to2.75 wt %, or 1 wt % to 2.5 wt % of the lubricating composition.

The diarylamine or alkylated diarylamine may be a phenyl-α-naphthylamine(PANA), an alkylated diphenylamine, or an alkylated phenylnapthylamine,or mixtures thereof. The alkylated diphenylamine may includedi-nonylated diphenylamine, nonyl diphenylamine, octyl diphenylamine,di-octylated diphenylamine, di-decylated diphenylamine, decyldiphenylamine and mixtures thereof. In one embodiment the diphenylaminemay include nonyl diphenylamine, dinonyl diphenylamine, octyldiphenylamine, dioctyl diphenylamine, or mixtures thereof. In anotherembodiment the alkylated diphenylamine may include nonyl diphenylamine,or dinonyl diphenylamine. The alkylated diarylamine may include octyl,di-octyl, nonyl, di-nonyl, decyl or di-decyl phenylnapthylamines.

The hindered phenol antioxidant often contains a secondary butyl and/ora tertiary butyl group as a sterically hindering group. The phenol groupmay be further substituted with a hydrocarbyl group (typically linear orbranched alkyl) and/or a bridging group linking to a second aromaticgroup. Examples of suitable hindered phenol antioxidants include2,6-di-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol,4-ethyl-2,6-di-tert-butylphenol, 4-propyl-2,6-di-tert-butylphenol or4-butyl-2,6-di-tert-butylphenol, or 4-dodecyl-2,6-di-tert-butylphenol.In one embodiment the hindered phenol antioxidant may be an ester andmay include, e.g., Irganox™ L-135 from Ciba. A more detailed descriptionof suitable ester-containing hindered phenol antioxidant chemistry isfound in U.S. Pat. No. 6,559,105.

In one embodiment the friction modifier may be selected from of longchain fatty acid derivatives of amines, long chain fatty esters, orderivatives of long chain fatty epoxides; fatty imidazolines; aminesalts of alkylphosphoric acids; fatty alkyl tartrates; fatty alkyltartrimides; fatty alkyl tartramides; fatty glycolates; and fattyglycolamides. The friction modifier may be present at 0 wt % to 6 wt %,or 0.01 wt % to 4 wt %, or 0.05 wt % to 2 wt %, or 0.1 wt % to 2 wt % ofthe lubricating composition.

As used herein the term “fatty alkyl” or “fatty” in relation to frictionmodifiers means a carbon chain having 10 to 22 carbon atoms, typically astraight carbon chain.

Examples of suitable friction modifiers include long chain fatty acidderivatives of amines, fatty esters, or fatty epoxides; fattyimidazolines such as condensation products of carboxylic acids andpolyalkylene-polyamines; amine salts of alkylphosphoric acids; fattyalkyl tartrates; fatty alkyl tartrimides; fatty alkyl tartramides; fattyphosphonates; fatty phosphites; borated phospholipids, borated fattyepoxides; glycerol esters; borated glycerol esters; fatty amines;alkoxylated fatty amines; borated alkoxylated fatty amines; hydroxyl andpolyhydroxy fatty amines including tertiary hydroxy fatty amines;hydroxy alkyl amides; metal salts of fatty acids; metal salts of alkylsalicylates; fatty oxazolines; fatty ethoxylated alcohols; condensationproducts of carboxylic acids and polyalkylene polyamines; or reactionproducts from fatty carboxylic acids with guanidine, aminoguanidine,urea, or thiourea and salts thereof.

Friction modifiers may also encompass materials such as sulphurisedfatty compounds and olefins, molybdenum dialkyldithiophosphates,molybdenum dithiocarbamates, sunflower oil or soybean oil monoester of apolyol and an aliphatic carboxylic acid.

In another embodiment the friction modifier may be a long chain fattyacid ester. In another embodiment the long chain fatty acid ester may bea mono-ester and in another embodiment the long chain fatty acid estermay be a triglyceride.

The lubricating composition optionally further includes at least oneantiwear agent. Examples of suitable antiwear agents include titaniumcompounds, tartrates, tartrimides, oil soluble amine salts of phosphoruscompounds, sulphurised olefins, metal dihydrocarbyldithiophosphates(such as zinc dialkyldithiophosphates), phosphites (such as dibutylphosphite), phosphonates, thiocarbamate-containing compounds, such asthiocarbamate esters, thiocarbamate amides, thiocarbamic ethers,alkylene-coupled thiocarbamates, and bis(S-alkyldithiocarbamyl)disulphides. The antiwear agent may in one embodiment include atartrate, or tartrimide as disclosed in International Publication WO2006/044411 or Canadian Patent CA 1 183 125. The tartrate or tartrimidemay contain alkyl-ester groups, where the sum of carbon atoms on thealkyl groups is at least 8. The antiwear agent may in one embodimentinclude a citrate as is disclosed in US Patent Application 20050198894.

Another class of additives includes oil-soluble titanium compounds asdisclosed in U.S. Pat. No. 7,727,943 and US2006/0014651. The oil-solubletitanium compounds may function as antiwear agents, friction modifiers,antioxidants, deposit control additives, or more than one of thesefunctions. In one embodiment the oil soluble titanium compound is atitanium (IV) alkoxide. The titanium alkoxide is formed from amonohydric alcohol, a polyol or mixtures thereof. The monohydricalkoxides may have 2 to 16, or 3 to 10 carbon atoms. In one embodiment,the titanium alkoxide is titanium (IV) isopropoxide. In one embodiment,the titanium alkoxide is titanium (IV) 2-ethylhexoxide. In oneembodiment, the titanium compound comprises the alkoxide of a vicinal1,2-diol or polyol. In one embodiment, the 1,2-vicinal diol comprises afatty acid mono-ester of glycerol, often the fatty acid is oleic acid.

In one embodiment, the oil soluble titanium compound is a titaniumcarboxylate. In a further embodiment the titanium (IV) carboxylate istitanium neodecanoate.

The lubricating composition may in one embodiment further include aphosphorus-containing antiwear agent. Typically thephosphorus-containing antiwear agent may be a zincdialkyldithiophosphate, phosphite, phosphate, phosphonate, and ammoniumphosphate salts, or mixtures thereof. Zinc dialkyldithiophosphates areknown in the art. The antiwear agent may be present at 0 wt % to 3 wt %,or 0.1 wt % to 1.5 wt %, or 0.5 wt % to 0.9 wt % of the lubricatingcomposition.

Extreme Pressure (EP) agents that are soluble in the oil includesulphur- and chlorosulphur-containing EP agents, dimercaptothiadiazoleor CS₂ derivatives of dispersants (typically succinimide dispersants),derivative of chlorinated hydrocarbon EP agents and phosphorus EPagents. Examples of such EP agents include chlorinated wax; sulphurisedolefins (such as sulphurised isobutylene), a hydrocarbyl-substituted2,5-dimercapto-1,3,4-thiadiazole, or oligomers thereof, organicsulphides and polysulphides such as dibenzyl-disulphide,bis-(chlorobenzyl) disulphide, dibutyl tetrasulphide, sulphurised methylester of oleic acid, sulphurised alkylphenol, sulphurised dipentene,sulphurised terpene, and sulphurised Diels-Alder adducts;phosphosulphurised hydrocarbons such as the reaction product ofphosphorus sulphide with turpentine or methyl oleate; phosphorus esterssuch as the dihydrocarbon and trihydrocarbon phosphites, e.g., dibutylphosphite, diheptyl phosphite, dicyclo-hexyl phosphite, pentylphenylphosphite; dipentylphenyl phosphite, tridecyl phosphite, distearylphosphite and polypropylene substituted phenol phosphite; metalthiocarbamates such as zinc dioctyldithiocarbamate and bariumheptyl-phenol diacid; amine salts of alkyl and dialkylphosphoric acidsor derivatives including, for example, the amine salt of a reactionproduct of a dialkyl-dithiophosphoric acid with propylene oxide andsubsequently followed by a further reaction with P₂O₅; and mixturesthereof (as described in U.S. Pat. No. 3,197,405).

Foam inhibitors that may be useful in the compositions of the inventioninclude polysiloxanes, copolymers of ethyl acrylate and2-ethylhexylacrylate and optionally vinyl acetate; demulsifiersincluding fluorinated polysiloxanes, trialkyl phosphates, polyethyleneglycols, polyethylene oxides, polypropylene oxides and (ethyleneoxide-propylene oxide) polymers.

Pour point depressants that may be useful in the compositions of theinvention include polyalphaolefins, esters of maleic anhydride-styrenecopolymers, poly(meth)acrylates, polyacrylates or polyacrylamides.

Demulsifiers include trialkyl phosphates, and various polymers andcopolymers of ethylene glycol, ethylene oxide, propylene oxide, ormixtures thereof.

Metal deactivators include derivatives of benzotriazoles (typicallytolyltriazole), 1,2,4-triazoles, benzimidazoles,2-alkyldithiobenzimidazoles or 2-alkyldithiobenzothiazoles. The metaldeactivators may also be described as corrosion inhibitors.

Seal swell agents include sulfolene derivatives Exxon Necton-37™ (FN1380) and Exxon Mineral Seal Oil™ (FN 3200).

INDUSTRIAL APPLICATION

The internal combustion engine may be a 4-stroke engine. The internalcombustion engine may or may not have an Exhaust Gas Recirculationsystem. The internal combustion engine may be fitted with an emissioncontrol system or a turbocharger. Examples of the emission controlsystem include diesel particulate filters (DPF), or systems employingselective catalytic reduction (SCR).

The lubricating composition may be characterised as having (i) a sulphurcontent of 0.5 wt % or less, (ii) a phosphorus content of 0.1 wt % orless, and (iii) a sulphated ash content of 0.5 wt % to 1.5 wt % or less.

The lubricating composition may be characterised as having at least oneof (i) a sulphur content of 0.2 wt % to 0.4 wt % or less, (ii) aphosphorus content of 0.08 wt % to 0.15 wt %, and (iii) a sulphated ashcontent of 0.5 wt % to 1.5 wt % or less.

The lubricating composition may be characterised as having a sulphatedash content of 0.5 wt % to 1.2 wt %.

The lubricating composition may have a total sulphated ash content of1.2 wt % or less.

The sulphur content of the lubricating composition may be 1 wt % orless, or 0.8 wt % or less, or 0.5 wt % or less, or 0.3 wt % or less. Inone embodiment the sulphur content may be in the range of 0.001 wt % to0.5 wt %, or 0.01 wt % to 0.3 wt %. The phosphorus content may be 0.2 wt% or less, or 0.12 wt % or less, or 0.1 wt % or less, or 0.085 wt % orless, or 0.08 wt % or less, or even 0.06 wt % or less, 0.055 wt % orless, or 0.05 wt % or less. In one embodiment the phosphorus content maybe 0.04 wt % to 0.12 wt %. In one embodiment the phosphorus content maybe 100 ppm to 1000 ppm, or 200 ppm to 600 ppm. The total sulphated ashcontent may be 0.3 wt % to 1.2 wt %, or 0.5 wt % to 1.1 wt % of thelubricating composition. In one embodiment the sulphated ash content maybe 0.5 wt % to 1.1 wt % of the lubricating composition.

In one embodiment the lubricating composition may be characterised ashaving (i) a sulphur content of 0.5 wt % or less, (ii) a phosphoruscontent of 0.15 wt % or less, and (iii) a sulphated ash content of 0.5wt % to 1.5 wt % or less.

The lubricating composition may be characterised as having at least oneof (i) a sulphur content of 0.2 wt % to 0.4 wt % or less, (ii) aphosphorus content of 0.08 wt % to 0.15 wt %, and (iii) a sulphated ashcontent of 0.5 wt % to 1.5 wt % or less.

The lubricating composition may be characterised as having a sulphatedash content of 0.5 wt % to 1.2 wt %.

As used herein TBN values are (total base number) measured by themethodology described in ASTM D4739 (buffer).

The lubricating composition may be characterized as having a total basenumber (TBN) content of at least 5 mg KOH/g.

The lubricating composition may be characterized as having a total basenumber (TBN) content of 6 to 13 mg KOH/g, or 7 to 12 mg KOH/g.

The lubricating composition may have a SAE viscosity grade of XW-Y,wherein X may be 0, 5, 10, or 15; and Y may be 20, 30, or 40.

The internal combustion engine disclosed herein may have a steel surfaceon a cylinder bore, cylinder block, or piston ring.

The internal combustion engine may have a surface of steel, or analuminium alloy, or an aluminium composite.

Typically the compression-ignition internal combustion engine has amaximum laden mass over 3,500 kg.

The following examples provide illustrations of the invention. Theseexamples are non-exhaustive and are not intended to limit the scope ofthe invention.

Examples

A series of lubricating compositions are prepared according to Table 1below. Each composition is formulated to deliver about 1% by weightsulfated ash (ASTM D874) and to have an overall TBN of about 10 (ASTMD2896).

TABLE 1 Diesel Lubricant Compositions¹ CEX1 EX1 EX2 10W-30 10W-30 15W-40Base Oil Balance to Balance to Balance to 100% 100% 100% Succinimidedispersant² 2.0 2.0 2.0 Aryl amine succinimide 0.85 0.85 0.85dispersant³ Overbased calcium sulphonate 0 0.58 0.58 (metal ratio ~10)“Neutral” calcium sulphonate 0 0.38 0.38 (metal ratio ~1.2) Overbasedcalcium sulphonate 0.53 0 0 (metal ratio ~3) Overbased magnesium 0.440.51 0.51 sulphonate Overbased Calcium sulfur- 0.43 0 0 coupled phenate“Neutral” Calcium sulfur-coupled 0.25 0 0 phenate Magnesium alkylenecoupled 0.37 0 0 phenol detergent Aromatic amine dispersant 0.33 0.330.33 viscosity modifier booster⁴ Secondary ZDDP (C3-6) 1.0 1.0 1.0Ashless Antioxidants⁵ 1.4 1.6 1.6 Other Additives⁶ 0.4⁷ 0.9 0.9 OCPViscosity Index Improver — 0.46 0.74 Pour Point Depressant 0.08 0.080.08 Detergent Substrate 1.42 0.83 0.83 Sulfated Ash 1.0 1.0 1.0 TBN 8.89.5 9.5 ¹All amounts shown above are in weight percent and are on anoil-free basis unless otherwise noted ²Succinated polyisobutylene (thepolyisobutylene has a vinylidene content of less than 25 wt %, and anumber average molecular weight of about 2200), aminated with ethylenepolyamine (TBN 60) ³Succinated polyisobutylene (the polyisobutylene hasa vinylidene content of less than 25 wt %, and a number averagemolecular weight of about 2200), aminated with polyaromatic amine⁴OCP(ethylene-propylene copolymer (having a number average molecularweight of about 8000) based DVM booster aminated with aromatic amine⁵Combination of alkylated diphenylamine, hindered phenol, and sulfurizedolefin ⁶Other additives include low levels of corrosion inhibitors,ashless TBN booster, and anti-foam agents ⁷No ashless TBN booster

The lubricating compositions are evaluated for both durability (i.e.anti-wear) and cleanliness (i.e. deposit control). Durability ismeasured in the GM 6.5L Roller Follower Wear Test (RFWT), an industrystandard wear test for measuring wear in diesel engines where sootaccumulates in the lubricant. Deposit control is evaluated in theCaterpillar 1N (CAT 1N) single cylinder engine test, an industrystandard test for measuring the ability of diesel lubricants to controloil consumption and prevent/reduce piston deposits especially top groovefill and top land heavy carbon. The results of these tests aresummarized in Table 2 below. It is known that lower viscosity grade oils(e.g. 10W-30) are more challenging to maintain durability; to betterdemonstrate the durability of the lubricating composition of theinvention, the lower viscosity grade example (EX 1) was evaluated in theRFWT. The higher viscosity lubricant (EX 2) is evaluated in the CAT 1Nengine test.

TABLE 2 Wear and Deposit Engine Tests CEX1 EX1 EX2 GM 6.5 RFWT Pin Wear,mils 0.24 0.09 CAT 1N Weighted demerits 311 Top Groove Fill 18 Top HeavyCarbon 1

The data demonstrates that the formulation with the combination of lowand high metal ratio sulphonates and ashless dispersant reduced wearwithout having a negative impact on deposit control. The resultsobtained indicate that the lubricating composition disclosed hereinprovides at least one of soot, reduced deposit formation, reduced wearand improved cleanliness to a heavy duty diesel engine.

It is known that some of the materials described above may interact inthe final formulation, so that the components of the final formulationmay be different from those that are initially added. The productsformed thereby, including the products formed upon employing lubricantcomposition of the present invention in its intended use, may not besusceptible of easy description. Nevertheless, all such modificationsand reaction products are included within the scope of the presentinvention; the present invention encompasses lubricant compositionprepared by admixing the components described above.

Each of the documents referred to above is incorporated herein byreference. Except in the Examples, or where otherwise explicitlyindicated, all numerical quantities in this description specifyingamounts of materials, reaction conditions, molecular weights, number ofcarbon atoms, and the like, are to be understood as modified by the word“about.” Unless otherwise indicated, each chemical or compositionreferred to herein should be interpreted as being a commercial gradematerial which may contain the isomers, by-products, derivatives, andother such materials which are normally understood to be present in thecommercial grade. However, the amount of each chemical component ispresented exclusive of any solvent or diluent oil, which may becustomarily present in the commercial material, unless otherwiseindicated. It is to be understood that the upper and lower amount,range, and ratio limits set forth herein may be independently combined.Similarly, the ranges and amounts for each element of the invention maybe used together with ranges or amounts for any of the other elements.

As used herein, the term “hydrocarbyl substituent” or “hydrocarbylgroup” is used in its ordinary sense, which is well-known to thoseskilled in the art. Specifically, it refers to a group having a carbonatom directly attached to the remainder of the molecule and havingpredominantly hydrocarbon character. Examples of hydrocarbyl groupsinclude: hydrocarbon substituents, including aliphatic, alicyclic, andaromatic substituents; substituted hydrocarbon substituents, that is,substituents containing non-hydrocarbon groups which, in the context ofthis invention, do not alter the predominantly hydrocarbon nature of thesubstituent; and hetero substituents, that is, substituents whichsimilarly have a predominantly hydrocarbon character but contain otherthan carbon in a ring or chain. A more detailed definition of the term“hydrocarbyl substituent” or “hydrocarbyl group” is described inparagraphs [0118] to [0119] of International Publication WO2008147704,or a similar definition in paragraphs [0137] to [0141] of publishedapplication US 2010-0197536.

As described hereinafter the number average molecular weight of thedispersant viscosity modifier and viscosity modifier has been determinedusing known methods, such as GPC analysis using polystyrene standards.Methods for determining molecular weights of polymers are well known.The methods are described for instance: (i) P. J. Flory, “Principles ofPolymer Chemistry”, Cornell University Press 91953), Chapter VII, pp266-315; or (ii) “Macromolecules, an Introduction to Polymer Science”,F. A. Bovey and F. H. Winslow, Editors, Academic Press (1979), pp296-312.

While the invention has been explained in relation to its preferredembodiments, it is to be understood that various modifications thereofwill become apparent to those skilled in the art upon reading thespecification. Therefore, it is to be understood that the inventiondisclosed herein is intended to cover such modifications as fall withinthe scope of the appended claims.

1-45. (canceled)
 46. A method of lubricating a compression-ignitioninternal combustion engine with a maximum laden mass over 2,700 kgcomprising supplying to the engine a lubricating composition comprising:an oil of lubricating viscosity, 1.5 wt % to 10 wt % of an ashlessdispersant, a 300 TBN or higher alkaline earth metal sulphonatedetergent having a metal ratio of 10 to 40, wherein the 300 TBN orhigher alkaline earth metal sulphonate detergent comprises a magnesiumsulphonate detergent, a 80 TBN or lower alkaline earth metal sulphonatedetergent having a metal ratio of 1 to 5, wherein the 80 TBN or loweralkaline earth metal sulphonate detergent comprises a calcium sulphonatedetergent, wherein the lubricating composition comprises 0 wt % to 0.2wt % of a phenolic based detergent, the ratio of 300 TBN or higheralkaline earth metal sulphonate detergent to 80 TBN or lower alkalineearth metal sulphonate detergent is 80:20 to 20:80, the total amount ofsoap delivered by the calcium sulphonate detergents is 0.4 wt % to 1.5wt % of the lubricating composition, and the lubricating composition hasa sulphated ash content of not more than 1.5 wt %.
 47. The method ofclaim 46, wherein the lubricating composition is characterised as having(i) a sulphur content of 0.5 wt % or less, (ii) a phosphorus content of0.1 wt % or less, and (iii) a sulphated ash content of 0.5 wt % to 1.5wt %.
 48. The method of claim 46, wherein the lubricating composition ischaracterised as having at least one of (i) a sulphur content of 0.2 wt% to 0.4 wt %, (ii) a phosphorus content of 0.08 wt % to 0.15 wt %, and(iii) a sulphated ash content of 0.5 wt % to 1.5 wt %.
 49. The method ofclaim 48, wherein the lubricating composition is characterised as havinga sulphated ash content of 0.5 wt % to 1.2 wt %.
 50. The method of claim46, wherein the lubricating composition is characterized as having atotal base number (TBN) content of at least 5 mg KOH/g.
 51. The methodof claim 50, wherein the lubricating composition is characterized ashaving a total base number (TBN) content of 7 to 10 mg KOH/g.
 52. Themethod of claim 46, wherein the total amount of soap delivered by thesulphonate detergents is 0.4 wt % to 1 wt % of the lubricatingcomposition.
 53. The method of claim 46, wherein the ratio of 300 TBN orhigher alkaline earth metal sulphonate detergent to 80 TBN or loweralkaline earth metal sulphonate detergent is 70:30 to 30:70.
 54. Themethod of claim 46, wherein the metal ratio of the 300 TBN or higheralkaline earth metal sulphonate detergent is 20 to
 30. 55. The method ofclaim 46, wherein the 300 TBN or higher alkaline earth metal sulphonatedetergent has a TBN of 350 to
 500. 56. The method of claim 46, whereinthe 80 TBN or lower alkaline earth metal sulphonate detergent has ametal ratio of 1 to
 3. 57. The method of claim 46, wherein the 80 TBN orlower alkaline earth metal sulphonate detergent has a TBN of 2 to 40.58. The method of claim 46, wherein the 300 TBN or higher alkaline earthmetal sulphonate detergent comprises a mixture of a calcium sulphonatedetergent having a metal ratio of 10 to 40, and the magnesium sulphonatedetergent having a metal ratio of 10 to
 40. 59. The method of claim 58,wherein the 300 TBN or higher alkaline earth metal sulphonate detergentmixture comprises a calcium sulphonate detergent having a metal ratio of16 to 20, and a magnesium sulphonate detergent having a metal ratio of12 to
 40. 60. The method of claim 58, wherein the 300 TBN or higheralkaline earth metal sulphonate detergent mixture comprises a calciumsulphonate detergent having a metal ratio of 22 to 25, and a magnesiumsulphonate detergent having a metal ratio of 14 to
 25. 61. The method ofclaim 46, wherein the lubricating composition comprises up to 0.1 wt %of a phenolic based detergent.
 62. The method of claim 46, wherein thelubricating composition comprises 0 wt % of a phenolic based detergent.63. The method of claim 46, wherein the lubricating composition furthercomprises a dispersant viscosity modifier.
 64. The method of claim 63,wherein the dispersant viscosity modifier is present at 0.01 wt % to 3wt %.
 65. The method of claim 63, wherein the dispersant viscositymodifier is an olefin copolymer further functionalised with a dispersantamine group.
 66. The method of claim 65, wherein the olefin copolymer isan ethylene-propylene copolymer.
 67. The method of claim 65, wherein theolefin copolymer has a number average molecular weight of 5000 to100,000.
 68. The method of claim 65, wherein the dispersant amine groupis derived from reacting the olefin copolymer with an acylating agentand an aromatic amine having a primary or secondary amino group.
 69. Themethod of claim 68, wherein the aromatic amine is selected from thegroup consisting of 4-aminodiphenylamine, aldehyde (typicallyformaldehyde) coupled 4-aminodiphenylamine, nitro-aniline, disperseorange-3 (DO3), or mixtures thereof.
 70. The method of claim 63, whereinthe dispersant viscosity modifier is present at 0.1 wt % to 1 wt %. 71.The method of claim 46, wherein the lubricating composition furthercomprises an antioxidant, wherein the antioxidant comprises a phenolicor an aminic antioxidant or mixtures thereof, and wherein theantioxidant is present at 0.1 wt % to 3 wt %.
 72. The method of claim 46further comprising a phosphorus-containing antiwear agent.
 73. Themethod of claim 46, wherein the ashless dispersant has a TBN on an oilfree basis of 50 to
 130. 74. The method of claim 46, wherein the ashlessdispersant comprises a succinimide dispersant, wherein the succinimidedispersant is present at 2.5 wt % to 6 wt %.
 75. The method of claim 74,wherein the succinimide dispersant comprises a polyisobutylenesuccinimide, wherein the polyisobutylene from which polyisobutylenesuccinimide is derived has a number average molecular weight of 350 to5000.
 76. The method of claim 75, wherein the polyisobutylenesuccinimide has a carbonyl to nitrogen ratio of 1:1 to 1:5.
 77. Themethod of claim 46, wherein the ashless dispersant comprises adispersant package of two or more dispersants.
 78. The method of claim77, wherein the dispersant package comprises: 0.1 wt % to 4 wt % withrespect to the lubricating composition of a borated polyisobutylenesuccinimide dispersant, wherein the polyisobutylene from which theborated polyisobutylene succinimide is derived has a number averagemolecular weight of 550 to 1150, and 0.1 wt % to 6 wt % with respect tothe lubricating composition of a polyisobutylene succinimide, whereinthe polyisobutylene from which polyisobutylene succinimide is derivedhas a number average molecular weight of 350 to
 5000. 79. The method ofclaim 78, wherein the polyisobutylene succinimide is derived from apolyisobutylene having a number average molecular weight of 1550 to 2500and is present at 0.1 to 2 wt %.